Composition dependent behavior in the ternary mixed magnetic insulator Co1−xMnyNix−yCl2·2H2O

• Published in: Physica. B, Condensed matter Vol. 488; pp. 24 - 31
• Main Authors: DeFotis, G.C., Hampton, A.S., Wallin, T.J., Trowell, K.T., Pothen, J.M., Welshhans, E.A., Havas, K.C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2016
• Subjects: Antiferromagnet; Hysteresis; Magnetic susceptibility; Magnetization; Randomness; Ternary mixed magnet; Randomness; Antiferromagnet; Magnetization; Ternary mixed magnet; Hysteresis; Magnetic susceptibility
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2016.02.015

The properties of ternary mixed magnetic Co1−xMnyNix−yCl2·2H2O are examined by dc magnetization and susceptibility measurements, from 1.8 to 300K as a function of composition. This is only the second ternary magnetic insulator so studied. The three transition metal chloride dihydrate components are known to differ in the degree of spin anisotropy and in the distribution of ferromagnetic and antiferromagnetic exchange interactions within and between strongly coupled chemical and structural chains. The Curie and Weiss constants, in χM=C/(T−θ) fits to high temperature susceptibilities, are compared with weighted averages of pure component values. The observed Weiss constant is almost uniformly less negative than calculated. Maxima in low temperature susceptibilities vary widely in presence and location with composition. Some compositions exhibit no susceptibility maximum, many exhibit one maximum, and three exhibit two maxima. A T(x,y) diagram is constructed. Magnetization vs field isotherms exhibit different shapes as a function of composition, with hysteresis markedly composition dependent. For three mixtures hysteresis loops are studied as a function of temperature. An activation process model does not describe the temperature dependence well.